JP2014052339A - Surface irregularity inspection device and surface irregularity inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface irregularity inspection device that precisely detects a fine irregularity defect existing in a measured object having surface quality similar to a mirror surface.SOLUTION: A surface irregularity inspection device 1 comprises: an irradiation section 2 that irradiates a measured surface of a measured object W moving in a horizontal direction with line light L obliquely from above; an imaging section 4 that images only reflection light R of regularly reflecting line light L of the line light L reflected at the measured surface; and a detection section 5 that detects irregularity of the measured surface on the basis of the reflection light R imaged by the imaging section 4. In the irradiation section 2, a light amount adjustment film 3 is formed that causes a light amount of line light L to be irradiated along a line orthogonal direction to be consecutively reduced, and the detection section 5 calculates a surface angle of the measured surface from which the reflection light R is emitted from luminance of the reflection light R and detects an irregularity state of the measured surface on the basis of the calculated surface angle θ.

Description

  The present invention relates to a surface unevenness inspection technique for inspecting a surface defect of a material to be inspected having a mirror-like flat surface such as a rolled aluminum plate.

  When a metal material such as aluminum is rolled using a rolling facility, streaky irregularities (rolling marks) may remain on the surface of the rolled sheet. If you try to inspect the rolled material with such streak-like irregularities using an optical inspection device, the reflected light irregularly reflected by the streak-like irregularities will be detected as the background by the inspection device, and you really want to detect it. Reflected light from defects such as threads and defective irregularities may be hidden, making it impossible to detect defects. For this reason, it is not possible to rely entirely on automatic inspection using an inspection machine for rolled materials such as aluminum, where streaky irregularities are particularly conspicuous, and still rely on visual inspection by skilled inspectors. Is the current situation.

However, since such a visual inspection has different judgment criteria depending on the inspector, the inspection result by the visual inspection has not only a personality but also a poor reproducibility. Further, human inspection processing capability is not as high as that of an inspection machine, and the inspection processing capability naturally has an upper limit. Therefore, when visual inspection is adopted, it takes a long time for inspection.
On the other hand, an optical automatic surface inspection apparatus using a high-speed camera has been developed in recent years. As one of them, there is a surface unevenness inspection apparatus for inspecting surface unevenness by a light cutting method using laser slit light as shown in Patent Document 1 and Patent Document 2. These surface unevenness inspection apparatuses are said to be capable of obtaining an image corresponding to the surface unevenness shape by adjusting the laser irradiation angle and the camera installation angle, and obtaining the unevenness shape from the image.

JP-A-4-348211 JP 2000-28339 A

By the way, in the surface unevenness inspection apparatus of Patent Document 1, when an aluminum rolled material is used as the material to be inspected, the reflected light is emitted only in the regular reflection direction in the aluminum rolled material. If the installation direction of the camera is slightly deviated from the regular reflection direction, an image of a light section line is hardly obtained, and there is a problem that a fine uneven defect formed on the surface cannot be inspected.
In addition, in the inspection using the optical cutting line, the inspection accuracy is not sufficient in terms of resolution, and even if the irradiation light intensity is increased until an image of the cutting line is obtained, the concave and convex defects of the aluminum rolled plate can be detected accurately. It is not possible. For example, when a light cutting line formed on an aluminum rolled plate having a plate width of 1000 mm or more is imaged by, for example, a line CCD camera, the number of pixels of the line CCD camera is currently about 1000 to 5000 pixels and detected. The height difference of the unevenness that can be made is limited to about 1 mm. This is extremely inadequate for inspecting a 10 μm level irregularity defect which is a problem in quality control.

  Furthermore, the technique of Patent Document 2 is to inspect defects on the surface by setting the elevation angle and azimuth angle of irradiation light in advance and photographing only scattered light from the defect portion. In the method of Patent Document 2, irradiation light is scattered at the edge of a boundary between a defective portion and a portion without a defect, and a defect is detected by photographing the scattered light. Or it is thought that a defect is detected by the reflected light reflected by the inclined surface with a large height difference formed in a defect.

However, there is a problem that even if the above-described minute unevenness defect is irradiated with such irradiation light, a luminance change corresponding to a minute surface angle change cannot be obtained, and scattered light sufficient to detect this defect cannot be obtained. is there.
The present invention has been made in view of the above problems, and has a surface unevenness inspection apparatus and surface unevenness inspection that can accurately detect fine unevenness defects present in an object having surface properties close to a mirror surface. It aims to provide a method.

In order to achieve the above object, the present invention takes the following technical means.
That is, the surface unevenness inspection apparatus according to the present invention includes an irradiation unit that irradiates line light obliquely from above to a measurement surface of a measurement object that moves in a horizontal direction, and line light reflected by the measurement surface. A surface unevenness inspection apparatus comprising: an image capturing unit that captures only reflected light of specularly reflected line light; and a detection unit that detects unevenness of a surface to be measured based on reflected light captured by the image capturing unit. The irradiation unit is provided with a light amount adjustment film for continuously reducing the light amount along the line orthogonal direction of the irradiated line light, and the detection unit receives the reflected light from the luminance B of the reflected light. The surface angle θ of the emitted measurement surface is obtained, and the uneven state of the measurement surface is detected based on the obtained surface angle θ.

  Preferably, when obtaining the surface angle θ of the surface to be measured from which the reflected light is emitted from the luminance B of the reflected light, the equation (1) may be used.

However, a and b are constants.

Preferably, the brightness of the reflected light reflected from the surface to be measured is measured for two or more surfaces to be measured whose surface angles are known, and the formula ( The constants a and b in 1) may be obtained.
Preferably, the irradiation unit emits line light in which three primary colors of R, G, and B are arranged along the longitudinal direction, and the imaging unit applies the reflected light to R, G, and B 3 The detection unit is configured to divide images into color components, and the detection unit uses the luminances _{R R} , B _G , and B _{B of} the reflected light that are captured by the imaging unit to divide into R components, G components, and B components. The surface angles θ _R , θ _G , and θ _B of the surface to be measured from which the reflected light is emitted are obtained, and the uneven state of the surface to be measured is detected based on the obtained surface angles θ _R , θ _G , and θ _B. It is good to be configured.

  The surface unevenness inspection method according to the present invention irradiates line light obliquely from above to the surface to be measured of a measurement object moving in the horizontal direction, and regularly reflects the line light reflected from the surface to be measured. This is a surface unevenness inspection method that captures only the reflected light of a light and detects the unevenness of the surface to be measured based on the reflected light that has been imaged. The irradiated line light has a continuous light quantity along the line orthogonal direction. The surface angle of the measured surface from which the reflected light is emitted is obtained from the brightness of the reflected light, and the uneven state of the measured surface is detected based on the obtained surface angle. It is characterized by doing.

  According to the surface unevenness inspection apparatus and the surface unevenness inspection method according to the present invention, it is possible to accurately detect minute unevenness defects present in an object to be measured having a surface property close to a mirror surface.

It is a perspective view of the inspection apparatus of a 1st embodiment. It is a figure which shows an example of a light quantity adjustment film. It is the figure which showed the reflected light image, the brightness | luminance, and the surface angle which were measured with the test | inspection apparatus of 1st Embodiment. It is the figure which compared the change of the brightness | luminance with respect to the surface angle by the presence or absence of the light quantity adjustment film. It is a flowchart which shows the surface unevenness inspection method. It is a figure which shows the result of an Example. It is a perspective view of the experimental apparatus used in order to derive this invention. It is the figure which showed the reflected light image, the brightness | luminance, and the surface angle which were measured with the experimental apparatus of FIG. (A) is a figure which shows the light quantity adjustment film of 2nd Embodiment, (b) is a figure which shows the change of the RGB component along the elongate direction of a light quantity adjustment film, (c) is a figure of 2nd Embodiment. It is a figure which shows the light quantity adjustment film of a modification.

[First Embodiment]
Hereinafter, an embodiment of a surface unevenness inspection apparatus 1 according to the present invention will be described with reference to the drawings.
The surface unevenness inspection apparatus 1 according to the present invention (hereinafter sometimes simply referred to as “inspection apparatus 1”)
The present invention relates to an inspection technique for inspecting fine unevenness formed on a surface of a metal having a high smoothness and a mirror surface like a rolled aluminum material.

  Specifically, the inspection apparatus 1 of the present invention inspects fine defects (defects with a small asperity gap of about 10 μm) formed on a wide rolled aluminum sheet having a width exceeding 1000 mm, for example. Such a fine defect (hereinafter referred to as a concavo-convex defect) could be detected by a visual inspection by a skilled worker in the conventional inspection technique, but in the inspection apparatus 1 of the present invention, an angle generated by the fine concavo-convex defect. The change is captured by the luminance change of the reflected light reflected by the defect.

First, before explaining the details of the inspection apparatus 1 of the present invention, the idea that the inventors have come up with the inspection apparatus 1 of the present invention will be described using experimental results and consideration thereof.
FIGS. 7A and 7B show an experimental apparatus 101 used in an experiment in which surface inspection was performed using an aluminum rolled plate as an object W to be measured.
This experimental apparatus 101 includes a mirror 102 (assuming an aluminum plate) in which a reflecting surface is directed in a horizontal direction and an inclination angle is variable, an LED irradiation unit 103 that irradiates the mirror 102 with line light L, a mirror And a camera 104 (imaging unit) that captures the line light L regularly reflected by the camera 102, and the camera 104 captures a reflected light image when the tilt angle of the mirror 102 is changed. The LED irradiation unit 103 can irradiate the line light L from obliquely above the mirror 102 (upper right in the case of FIG. 7A), and the line light L irradiated from the LED irradiation unit 103 is irradiated. It is made into the line shape extended along the width direction (up-down direction in the planar view shown in FIG.7 (b)) orthogonal to a direction. Further, the camera 104 can shoot the reflected light R obtained by regular reflection of the line light L from the LED irradiation unit 103 to the mirror 102 (the line light L and the reflected light R are mirrors 102). It is installed at a position symmetrical to the normal line).

In the experimental apparatus 101 as shown in FIG. 7, the reflected light image captured when the tilt angle of the mirror 102 is −0.25 degrees and the reflected light image captured when the tilt angle of the mirror 102 is +0.5 degrees. The reflected light image is shown in FIG.
As shown in FIG. 8A, in the reflected light image reflected by the mirror 102 having the inclination angle of −0.25 degrees, the reflected light R is reflected from the reflected light image when the inclination angle is +0.5 degrees. It can be seen that the position of the bright line shown is shifted to the side with the larger X position (the side with the larger pixel at the X position), and the position of the bright line on the reflected light image changes when the tilt angle of the mirror 102 is different.

  In the reflected light image of FIG. 8A, the reference line P is set along the direction across the image, in other words, the direction orthogonal to the line of the line light L, and the brightness of the bright line measured along the reference line P is set. When the measured luminance is plotted with respect to the position (X position) on the reference line P, the result is as shown in FIG. As shown in FIG. 8B, the change in luminance when the inclination angle is -0.25 degrees, and the luminance when the inclination angle is +0.5 degrees are about 290 to 330 or 315 in the X position. In the vicinity of ˜355, the luminance tends to increase rapidly. For example, if the brightness when the tilt angle is −0.25 degrees is taken as an example, the brightness rapidly increases from 20 to 220 at the X position near 290, and the brightness is the same as 220 at the X position of 290 to 330. The value is maintained, and when the X position exceeds 330, it shows a change that rapidly decreases again from 220 to 20, and the shape of the change curve is a table that protrudes upward in a rectangular shape at both inclination angles. It has a curved shape.

That is, as is clear from FIG. 8B, the luminance change curve when the inclination angle is +0.5 degrees is horizontally moved by a width of +25 pixels in the direction in which the X position increases. It is a luminance change curve at 0.25 degrees.
Here, focusing on the position where the change curves of both tilt angles intersect on the reflected light image, for example, the position where X is 320 pixels, the relationship between the tilt angle of the mirror 102 and the brightness is summarized as shown in FIG. As shown in (c).

As shown in FIG. 8C, at the position where X is 320 pixels, the luminance remains small until the tilt angle of the mirror 102 is −0.7 degrees to −0.4 degrees, but the tilt angle is − When the angle exceeds 0.4 degrees, the luminance starts to increase, and the luminance sharply increases while the inclination angle is as short as 0.2 degrees from -0.3 degrees to -0.1 degrees. Then, the increase in luminance becomes dull from the vicinity where the inclination angle exceeds −0.1 degrees, and the luminance remains constant again when the inclination angle is +0.1 degrees or more.

The above-described relationship between the tilt angle of the mirror 102 and the brightness includes a very important fact.
In other words, if the reflected light image is captured by the camera 104 while changing the tilt angle of the mirror 102, the relationship between the tilt angle of the mirror 102 and the brightness can be obtained in advance, and the camera can be calculated back using this relationship. It is possible to detect the tilt angle of the surface whose tilt angle is unknown from the brightness photographed at 104, in other words, the surface angle of the measurement surface of the object W to be measured.

In the measurement of the surface angle based on this luminance, the surface angle and depth of fine irregularities are required with high accuracy regardless of the resolution of image processing. However, if the surface angle is to be calculated backward from the luminance with the apparatus configuration shown in FIG. 7, the surface angle range is narrower than the luminance range that can be calculated backward in the graph of FIG. It becomes difficult to detect with high accuracy.
Therefore, in the surface unevenness inspection apparatus 1 according to the first embodiment of the present invention, the light amount adjustment film 3 that gradually reduces the light amount of the line light L irradiated from the irradiation unit 2 along the moving direction of the object W to be measured. Is provided.

  In other words, the surface unevenness inspection apparatus 1 includes the irradiation unit 2 that irradiates the line light L obliquely from above and the line light L reflected from the measurement surface with respect to the measurement surface of the object W that moves in the horizontal direction. Among them, an imaging unit 4 that captures only the reflected light R of the line light L that is regularly reflected, and a detection unit 5 that detects unevenness of the surface to be measured based on the reflected light R captured by the imaging unit 4 are provided. The irradiation unit 4 is configured to irradiate the line to be measured with the line light L formed in a straight line along the direction orthogonal to the moving direction of the object W to be measured. 2 is provided with the light amount adjusting film 3 described above.

Next, the irradiation part 2, the camera 4, the detection part 5, and the light quantity adjustment film 3 which comprise the surface unevenness | corrugation inspection apparatus 1 are demonstrated in detail using FIG.
As shown in FIG. 1, the irradiating unit 2 has a direction perpendicular to the moving direction of the measured object W with respect to the measured surface of the measured object W moving in the horizontal direction (a width direction orthogonal to the irradiated direction). ) Is a light source capable of irradiating linearly extending line light L. Although not shown, the irradiator 2 employs a light emitter in which a plurality of LEDs are arranged in a line. The irradiation unit 2 includes a laser projector that emits a spot-shaped laser beam, and an irradiation structure that includes a cylindrical lens that collects the spot light projected from the laser projector and changes it into a line-shaped laser beam. It can also be adopted. Moreover, the irradiation part 2 may be formed with the long rod-like fluorescent lamp.

  As shown in FIG. 2, the light amount adjustment film 3 gradually reduces the line light L irradiated from the irradiation unit 2 to the object W to be measured according to the position, so that the change rate of the luminance with respect to the surface angle is changed. It is to make it smaller. The light amount adjustment film 3 is attached to the surface of the irradiation unit 2 facing the object to be measured W or is disposed at a certain distance from the surface, and is irradiated from the irradiation unit 2. The line light L can be reduced along the line orthogonal direction (the amount of light along the line orthogonal direction of the line light L is continuously reduced). The light intensity adjustment film 3 has a transparency adjusted so that the density is “gradually darker”, “thinner”, or “gradually darker and then lighter” along the direction perpendicular to the line direction. Has been. Specifically, as the light amount adjusting film 3, a light transmissive film having a gradation pattern in which the transparency gradually changes along the moving direction of the measurement object W can be used.

As described above, since the irradiation unit 2 irradiates the line light L in a direction orthogonal to the moving direction of the object to be measured W, the luminance of the line light L changes along the moving direction of the object to be measured W. It has become a light to do.
As shown in FIG. 1, the object W to be measured is made of a rolled material such as aluminum, stainless steel, a high-luminance steel plate, a material such as a silicon substrate or a glass substrate, and light (incident on the mirror surface) by polishing or plastic working. A surface to be measured capable of reflecting light). Such a surface to be measured is capable of specularly reflecting the incident line light L, and the specularly reflected line light L is incident on the camera 4 as reflected light R. In addition, the to-be-measured object W of the example is a rolled aluminum material, and the measured surface is an aluminum rolled surface.

The imaging unit (camera 4) is composed of a CCD camera (area camera), and has a width so that the reflected light R of the line light L regularly reflected by the surface to be measured of the object W to be measured is reflected in the approximate center of the imaging screen. A wide range having a sufficient length in the direction and the longitudinal direction can be imaged. Further, the camera 4 is provided at a position opposite to the irradiation unit 2 with respect to the measurement surface (a position where the line light L and the reflected light R are in line symmetry with respect to the normal S of the measurement surface). Thus, the reflected light R specularly reflected by the surface to be measured can be photographed. The reflected light image captured by the camera 4 is sent to the detection unit 5.

The detection unit 5 is configured by a personal computer or the like, and detects the surface state (surface irregularity state) of the surface to be measured based on the reflected light image captured by the camera 4. Specifically, the detection unit 5 can calculate the surface angle of the surface to be measured based on the reflected light image, and integrate the calculated surface angles to evaluate the uneven state (surface roughness) of the surface to be measured. It is like that.
For example, as in the case of FIG. 8, the light amount adjustment described above is performed on the reflected light image of the mirror 102 with the inclination angle of −0.25 degrees and the reflected light image of the mirror 102 with the inclination angle of +0.5 degrees. When an image is taken by the camera 4 of the surface unevenness inspection apparatus 1 having the film 3, a reflected light image as shown in FIG.

  In FIG. 3A as well, bright lines are confirmed on the respective reflected light images as in FIG. 8A. The position of the bright line is shifted to the larger X position at the position where the inclination angle is −0.25 degrees than the position where the inclination angle is +0.5 degrees. Therefore, when the change in luminance in the reflected light image observed in FIG. 3A is measured along the reference line P and the measured luminance is plotted against the X position, as shown in FIG. Become.

The luminance change curve shown in FIG. 3B is not a trapezoidal shape as in FIG. 8B but a triangular shape protruding upward. That is, in FIG. 3B, the change in luminance with respect to the X position is not as steep as in FIG. 8B, and the luminance changes gradually as the X position increases.
Here, as in FIG. 8, in FIG. 3B, focusing on the position where X is 320 pixels, for example, the tilt angle of the mirror 102 is set in the range of −0.7 to +0.5. FIG. 3C shows a summary of the change in luminance when the change is made with respect to the tilt angle of the mirror 102.

As shown in FIG. 3 (c), when the change in luminance with respect to the surface angle is obtained using the inspection apparatus 1 provided with the light amount adjustment film 3, the increase in the surface angle is handled in the same manner as in FIG. 8 (c). A change curve in which the luminance gradually increases appears, but the manner of change is more gradual.
That is, as apparent from FIG. 4, when an inspection apparatus (experiment apparatus 101) that does not have the light amount adjustment film 3 is used, the inclination angle is −0 as indicated by a square mark in the figure. The brightness increases sharply in a short time of 0.2 degrees from .3 degrees to -0.1 degrees. However, when the inspection apparatus 1 having the light amount adjustment film 3 is used, as shown by a diamond mark in the drawing, the mirror 102 has an inclination angle of 0.5 to −0.3 degrees to +0.2 degrees. The luminance changes slowly and linearly over a wide angle range of degrees. From this, it can be seen that the measurement range of the surface angle can be expanded by providing the light amount adjustment film 3 even if the luminance has the same change width.

  For example, in the case of the inspection apparatus (inspection apparatus 1 of the present embodiment) provided with the light amount adjustment film 3, for the angle range of 0.5 degrees described above, the following is made between the luminance B and the surface angle θ. The relationship (linear form) as shown in Equation (1) is established.

However, a and b are constants.

  For this equation (1), the brightness of the reflected light R reflected by the measured surface is measured for two or more measured surfaces with known surface angles, and two or more sets of measured data are obtained. If used, the constants a and b can be obtained. Therefore, the equation (1 ′) can be derived by obtaining a linear linear regression curve from the experimental data of FIG. 4 described above.

  Since this equation (1 ′) represents the luminance B by the surface angle θ of the surface to be measured, the surface angle θ can also be represented by the luminance B as in equation (2).

  The slope shown as “0.00287” and the intercept shown as “−0.353” in Equation (2) described above change to various values depending on how the light amount adjustment film 3 is shaded and arranged. However, if a predetermined light amount adjustment film 3 is used and the surface angle θ derived from the equation (2) corresponding to the light amount adjustment film 3 is used, the surface state (unevenness state) of the surface to be measured can be changed to the surface angle under the same measurement conditions. It is possible to make a relative comparison and judgment from the viewpoint.

  If the surface angle θ derived from the equation (2) and the measurement interval Δx along the moving direction are used, the height of the surface to be measured can be obtained by the equation (3), and the same measurement is performed using this height. The surface state (unevenness state) of the surface to be measured can be relatively compared and determined under the conditions.

By providing the light amount adjusting film 3 described above, the change in the luminance B with respect to the surface angle θ of the surface to be measured can be reduced, and the surface angle θ of the surface to be measured can be further increased based on the luminance B imaged by the camera 4. Measurements can be made over a wide range and with high accuracy (with high resolution).
Further, the detection unit 5 can calculate the height of the surface to be measured (surface unevenness state) by integrating the surface angle θ calculated as described above as shown in Equation (3). Using the calculated height of the measured surface, the surface state (unevenness state) of the measured surface can be relatively compared and determined.

Next, the signal processing performed in the detection unit 5, in other words, the surface unevenness inspection method of the present invention will be described with reference to FIG.
As shown in FIG. 5, when measuring the surface state of the workpiece W, first, the workpiece W (in the example shown, an aluminum plate) is moved along the horizontal direction, in other words, during rolling conveyance. The surface of the aluminum plate is inspected (S1). Then, the line light L is irradiated from the irradiation unit 2 to the surface to be measured of the object W to be measured, and the reflected light R reflected from the surface to be measured of the object W to be measured is continuously imaged using the camera 4 ( S2). This imaging is continuously performed until the measurement of the workpiece W is completed.

For example, among the imaging data of the reflected light image captured from the camera 4 to the detection unit 5, an i-th (i-th frame) reflected light image is captured (S3), and image processing is performed on the i-th reflected light image. .
With respect to the i-th reflected light image, a bright part extraction process, a labeling process, and the like are performed, and the captured reflected light, that is, the bright lines (coordinates (x1, 0) to (x1, y)) in the captured image are extracted. Thereafter, the process proceeds with respect to the luminance data of one pixel ((coordinate (x1, n)) existing on the bright line.

  First, after setting n = 0, the luminance of the pixel (x1, n) is acquired (S4), and the acquired luminance is created in advance as a graph showing the relationship between the luminance B and the surface angle θ (FIG. 4) ”, the surface angle θ of the portion corresponding to the pixel (x1, n) is calculated. Then, the height of the measured surface is obtained by integrating the obtained surface angle θ (S5). Next, using the obtained height of the surface to be measured, the quality of the surface irregularity state is determined based on whether or not these values exceed a predetermined threshold (S6).

By performing the above processing (S4 to S6) for all the pixels of the bright line, it is determined whether the surface unevenness state on one line is good or bad (S7).
Further, such operations of S1 to S7 are performed not only on the i-th reflected light image but also on all reflected light images (all frame images) that are continuously captured. In other words, after the operations of S1 to S7 are performed on the i-th (i-th frame) reflected light image, all the consecutively captured images are performed, such as the i + 1-th (i + 1-th frame) reflected light image. By performing the process on the reflected light image, it is possible to evaluate the change of the surface unevenness state of the surface to be measured of the object W to be measured over time (S8).
[Second Embodiment]
Next, the inspection apparatus 1 of 2nd Embodiment is demonstrated.

In the inspection apparatus 1 according to the second embodiment, the irradiation unit 2 irradiates the line light L formed by arranging the three primary colors R, G, and B along the longitudinal direction, and the imaging unit 2 emits the reflected light R. red, green, and is configured to image divided into components of blue three colors, R component detection unit 5 by the imaging unit 2, G-component, the luminance B _R of the reflected light R is captured is divided into component B , B _G , B _B , surface angles θ _R , θ _G , θ _B of the measured surfaces from which the reflected light R is emitted are obtained, and based on the obtained surface angles θ _R , θ _G , θ _B It is configured to detect the uneven state of the surface.

  Specifically, in the irradiation unit 2 provided in the inspection apparatus 1 of the second embodiment, one end side (one end side along the longitudinal direction) of the line is red (primary color R), and the center side is green (primary color G). The other end side may be blue (primary color B) and three colors, or light emitting diodes having the three primary colors R, G, and B may be repeatedly arranged in a predetermined order several times. It may be a thing. Furthermore, what provided the film (light quantity adjustment film 3) separately coated by the three primary colors on the surface of the irradiation part 2 may be used. For example, as shown in FIG. 9A, purple (P) → blue (B) → green (G) along the short direction of the film (vertical direction in the drawing) as shown in FIG. A film whose color changes in the order of yellow (Y) → red (R) can be used. If such a film is used, as the position along the short direction changes as shown in FIG. 9B, the R component, G component, and B component of the light transmitted through the film differ from each other by 120 °. It changes according to a sine curve with.

Further, for example, a general color CCD camera can be used as the image pickup unit (camera 4) described above, and the reflected light is divided into three color components of R, G, and B to be picked up and output. Yes. Furthermore, the detection unit 5 includes three detection units 5 described in the first embodiment in accordance with the three primary colors.
By using such an inspection apparatus 1 of the second embodiment, it is possible to detect the surface state of one reflected light image by dividing it into three components of an R component, a G component, and a B component. It is possible to realize a process in which the inspection using the monochromatic line light L is simultaneously performed three times. Therefore, it corresponds to what has been done. The amount of information on the surface state that can be detected at a time increases to about three times, and the detection accuracy of the surface state is greatly improved.

In addition, when the film as shown in FIG. 9A is used to detect the three components of the R component, the G component, and the B component as described above, the luminance is the highest among the three components according to the position. It is possible to use a component that greatly changes, and it is possible to further improve the detection accuracy of the surface state because the change in luminance is large.
For example, in FIG. 9B, when light is detected at a position indicated by “A” in the drawing, the luminance of the R component is detected at the position “A” when the surface state is detected using the R component. Is not so large, the detection accuracy is inevitably lowered when the surface state is detected from such brightness. However, if the G component and the B component other than the R component are adopted, the change in luminance at the position “A” can be greatly taken for both components, so that the surface state detection accuracy can be increased.

Furthermore, the method of detecting the surface state by dividing into three components of R component, G component, and B component, in other words, the method using a color film can be combined with the above-described method using a black and white film. For example, as shown in FIG. 9C, the film is divided into a plurality of regions along the longitudinal direction (the left-right direction in FIG. 9C). Then, purple (P)-> blue (B)-> green (G)-> yellow (Y)-> red (R) along the short direction (vertical direction in Fig. 9 (c)) within each region. “Color (color)” is changed, and “brightness (lightness)” is changed in the order of dark → light → dark along the long direction. In this way, if a change in shade and a change in color are provided along the directions orthogonal to each other, not only the surface state along the moving direction of the object W can be detected using a single film, but also the moving direction and The surface state along the vertical direction can also be detected, and the surface state of the workpiece W can be accurately detected for each finer region.

Next, the function and effect of the inspection apparatus 1 of the present invention will be described in more detail using the embodiment shown in FIG.
FIG. 6A shows an image of the reflected light R of the line light L irradiated from the irradiation unit 2 using an LED on the surface to be measured W of a workpiece W made of a rolled aluminum material. . Note that the surface to be measured has a step difference that rapidly decreases as it moves in the moving direction as an uneven defect.

Moreover, the part shown with the dotted line in the figure of Fig.6 (a) has shown the area | region for a detection. While the detection area was fixed, the reflected light images in this area were taken continuously at regular intervals. As an example, FIG. 6B shows images of the 30th, 35th, 40th, 45th, and 50th frames from the start of imaging.
As shown in FIG. 6B, as the imaging of the frame proceeds from the 30th frame to the 50th frame, the position of the bright line changes to the side with the larger X position on the reflected light image (the right side in the figure). It can be seen that when the bright line reaches a position where the unevenness of the measurement surface is provided, the surface angle θ calculated from the reflected light changes and the position of the bright line changes on the image.

For the five region images shown as an example in FIG. 6B, the luminance is measured along the reference line P indicated by the alternate long and short dash line in FIG. Shown in
Next, in FIG. 6C, the luminance change as shown in FIG. 6D is obtained by extracting the luminance observed at a predetermined X position (for example, X = 345) on the reflected light image. It becomes possible.

  In FIG. 6D, the horizontal axis represents the number of imaging frames, and corresponds to the imaging time one-on-one. Since the aluminum plate as the object to be measured W is conveyed at a predetermined speed, the horizontal axis in FIG. 6D can also be considered as the position on the object to be measured W irradiated with the line light L. The vertical axis in FIG. 6D is the luminance value of the reflected light R at that time. FIG. 6D plots luminance data when the X position in FIG. 6C is at 342 pixels, 343 pixels, 344 pixels, and 345 pixels.

  By applying Equation (2) to the luminance data of FIG. 6C, a transition curve of the surface inclination angle θ plotted with the square marks in FIG. 6E can be obtained. By applying Equation (3) to the transition curve of the surface inclination angle θ, it is possible to obtain a transition curve of the surface irregularity height change plotted with rhombus marks. The uneven height change obtained by Expression (3) is a relative change value. It can be seen that uneven defects such as “sledge” or “swell” on the surface of the workpiece W can be detected with high accuracy based on the uneven height change obtained by the equation (3).

As described above, according to the surface unevenness inspection apparatus of the present invention, it becomes possible to detect fine unevenness defects formed on a wide inspection object by distinguishing them from rolling marks.
By the way, it should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 Inspection device (surface irregularity inspection device)
DESCRIPTION OF SYMBOLS 2 Irradiation part 3 Light quantity adjustment film 4 Imaging part 5 Detection part W Measured object L Line light R Reflected light P Reference line B Luminance θ Surface angle h Height 101 Experimental apparatus 102 Mirror 103 LED irradiation part 104 Camera

Claims (5)

An irradiation unit that irradiates line light obliquely from above to the measurement surface of the object to be measured that moves in the horizontal direction, and only the reflected light of the line light that is regularly reflected out of the line light reflected by the measurement surface is imaged. A surface unevenness inspection apparatus comprising: an imaging unit; and a detection unit that detects unevenness of a surface to be measured based on reflected light imaged by the imaging unit,
The irradiation unit is provided with a light amount adjustment film that continuously reduces the light amount along the line orthogonal direction of the irradiated line light,
The detection unit is configured to obtain a surface angle of the surface to be measured from which the reflected light is emitted from the brightness of the reflected light, and detect an uneven state of the surface to be measured based on the obtained surface angle. An apparatus for inspecting surface irregularities characterized by comprising: 2. The surface irregularity inspection apparatus according to claim 1, wherein when the surface angle of the surface to be measured from which the reflected light is emitted is obtained from the luminance of the reflected light, the equation (1) is used.
Where B is the luminance, θ is the surface angle, and a and b are constants.   With respect to two or more measured surfaces with known surface angles, the brightness of the reflected light reflected by the measured surface is measured, and the constant a in the equation (1) is used using two or more sets of measured data. , B are obtained, The surface unevenness inspection apparatus according to claim 2. The irradiation unit irradiates line light in which three primary colors of R, G, and B are arranged along the longitudinal direction;
The imaging unit is configured to divide the reflected light into three color components of R, G, and B and to capture the image,
The detection unit is configured to detect the surface angle θ _R of the surface to be measured from which the reflected light is emitted from the luminances B _R , B _G , and B _{B of} the reflected light imaged by the imaging unit separately for the R component, G component, and B component , Θ _G , θ _B are obtained, and the uneven state of the surface to be measured is detected based on the obtained surface angles θ _R , θ _G , θ _B. 4. The surface unevenness inspection apparatus according to any one of 3 above. By irradiating the surface to be measured of the object to be measured moving in the horizontal direction obliquely from above, only the reflected light of the regularly reflected line light out of the line light reflected by the surface to be measured is imaged. A surface unevenness inspection method for detecting unevenness of a surface to be measured based on reflected light,
The irradiated line light is such that the light quantity along the line orthogonal direction decreases continuously,
A surface unevenness inspection method, wherein a surface angle of a surface to be measured from which the reflected light is emitted is obtained from the brightness of the reflected light, and an uneven state of the surface to be measured is detected based on the obtained surface angle.